Lonely Raven wrote: That's exactly the one I'm listening to, and it's excellence is exactly why I wish I could turn it up more. There is something in there the 2 watts just isn't getting me - I guess it's the weight I'm missing.

The CKC with HSU Mid Bass Module will provide all the weight you could want from the CKC. Place your Mains where they do Mids & Highs best (Don't worry about the Bass). Connect the MBM to the CKC via speaker level connections and dial in any amount of wonderful Mid-Bass you desire to suite your room and taste.

The sound stage will be much bigger and much more powerful without Maxing out the volume on the CKC.

I'm hoping to get back to reworking the garage today so I can start on my diffuser projects. I'm not sure I have enough wood for a prototype, so I might just make a couple smaller diffusers to start with...

My garage setup is one of those old Denon CD players with discrete power supplies in a copper chassis that has trouble opening and closing the tray - going into some 100 watt transistor "reference" amp from my Dad's old home studio, into some budget studio monitors that I rebuilt with better tweeters in a crossoverless design, with a waterlogged Klipsch 10" subwoofer. This is my "second system" ::)

After the Decware amp into Decware speakers with the Maelstrom X 21" sub powered with 2k watts, it's a serious step down. LOL

Sounds like a great garage system I guess you really don't have to worry about hurting it with all of the saw dust you'll be running through it soon from the sounds of it. Hope to see what you've come up with when you get one done. For now I just have to be a Mystery amp want ta be at least until I get my house and garage re-roofed this spring. Some times timing in life seems off! I guess I should be glad that the roof didn't end up a surprise after the Mystery amp although I would be able to listen to rain drops keep falling on my head in 3d and plenty of spaciousness. Ha Ha!

Bet your excited! Enjoy that thing I'll be looking forward to hearing about it once you have had time to give a serious listen to it in your setup.

But that's actually not true... With orders placed but no amplifiers built yet there was plenty of time to second guess yourself. It's the most difficult test you'll ever have to pass as it continually challenges your subjective likes and dislikes. Fortunately I do OK in that department because I explicitly trust my ears. And I'm happy to report there is nothing I would want to change about the way the amp sounds.

Sound, is however only part of the game. Usability, reliability, ease to build... etc. Even though I have the first Mystery Amp as the build sample and it has one of my best layouts ever... it can still be improved. You want everything to be easy to copy since we'll be building a lot of them. So in that light I began to see a new layout. The more I stared at the original layout, the more new layout appeared.

Keep in mind, the differences are subtle but just enough to tip the scale towards perfection - the obvious goal. It looks slightly cleaner because it is, and will therefor be slightly easier to build.

Amps are built in three stages. The first is assembling the chassis and all the parts that go on it. The second (shown above) is called the base layout. It consists of all the main power and ground paths and basically makes up a completed and working power supply. The third is adding components on the tube sockets to create the audio circuit.

While I was at it I also spent a great deal of time wrestling with what to do about the bias circuit. I spent so much time (days) getting the original to work the way I wanted it to, and now I'm second guessing it. Compared to the vast majority of bias circuits I really felt it was a masterpiece of form and function. It however shared a potentially fatal flaw just like most bias circuits that place the potentiometer in series with the bias voltage. If the tube draws excessive amounts of grid current it's possible the rating of the potentiometer can be exceeded and cause it to open (fail). That would remove the negative bias voltage from the grid and let your tube self destruct in a matter of minutes. While the chances of this happening are only 1 in 1000, I plan to make 1000 of these amps.

So with this in mind, I had to redesign the bias supply from scratch so that the potentiometers were only used to pull voltage to ground for both the supply and the balance. Sounds simple but it actually wasn't. Nevertheless, now it will be impossible for the condition of the pot or failure of a pot to kill the negative bias voltage. Instead, it will just let the negative voltage go to max which is enough to completely shut off both tubes at the same time... and that's a big improvement over letting the voltage go to zero since doing so causing the tubes to draw the full current of the power transformer until they melt or the transformer melts or the fuse blows, whichever comes first.

Anyway, a glimpse into the design process continues...

The amp pictured above is on my bench and nearing completion to become the new sample that everyone will use to build from. We're going to start building the first production units directly after the holidays.

I can hardly wait to see how well this amp is received. I'm committed to it. Even if everyone hated it, we'd do whatever it took to make it great. I don' think anyone's going to hate it though.

Steve…thanks for the update. Sounds like this explains the delay in production for the first Mystery amps. I can’t speak for everyone else, but I am ok waiting for the perfect Mystery amp. Sounds like you are putting the finishing touches on this beauty. For those of us in the last 5% of waiting, I suppose this is the excitement that goes along with being early adopters for the new amp.

Do you expect any of the changes to impact the sound profile of the amplifier? Happy listening and looking forward to your impressions.

Looks nice and neat. I would imagine keeping it clean will also aid in any trouble shooting that may need to be done 30 years from now. Looks like a nice simple layout. I know it is my un-educated electronic eye speaking here. I knew there was a reason I should of went into electronics instead of electricity classes years ago. I am envious for all that will be receiving one shortly. Steve great explanation about your design philosophy it really is why I plan on owning a Mystery amp in the future. Of course the sweet sound to! Looking forward to hearing every ones impressions of this wonderful amp.

Steve, thanks for your input/update. I too, can't speak for anyone else...but, when you think it is ready to ship...then it is ready to ship. I know you're making it as fool proof as it can be for a Music Lover Laymen like me.

I so look forward to it being soooo NOT Solid State (not a circuit board in sight)....right out of the gate.....with the headroom I now crave. The seasoning over time, I know will make me turn my head with a smile. -S